Valve for rock drills



Sept. 7, 194s. H. o. mss-UM 2,448,875

VALVE FOR'ROCK DRILLS -INVENTOR ATTORNEY Sept. 7,l 194s. H. o. FOSSUM 2,448,815

VALVE Foa Roux DRILLs Filed Feb. 23. 1944 2 Sheets-Sheet 2 INVENTOR fA/Py 0. @man .WHY ATTORNEY Patented Sept. 7, 1948 UNITED FS TATES PAT'ENT 0F Fil CE y lVALVE Fon noon DRILLs i 'Henry 0. Fossum, Detroit, Mich., Jassigner lto :Chicago Pneumatic Tool lCompany, New York, N. Y., arcorporation of New [Jersey f A Application February 23,. 19244, seriamo. 523,523

This invention relates Yto rock drills .and more particularly to `automatica'lly operated distributing valves for rock drills of the uid `driven percussive type.

The main object `of the invention l'is toprovide 1 Claim.. (Cl. 121-19) alpositively .and automatically :actuated distributing valve which, together with cooperating valve seats and motive fluid ports and passages, is of such ellcient `design and `arrangement that the motive `fluid will flow .with substantially full power'from the lfluid source to `the piston for highly effective yoperal'fiezni of tthe latter.

'Lt is ltherefore yan important object of this invention sto arrange the ,distributing valve and its associated seats and fluid ports ,to #produce ;substantially a streamlined lflcw of the nmotive lluid to the hammer piston.

Another object .is to have :a distributing valve provided Awith opposite holding faces fand characterized by the fact :that after being -tripped in either direction, the face which, priorto the tripping operation, acted as a holding earea ceases to function as .such .and the opposite race becomes a holding Larea.

A further object is -to lprovide a valve vof the kind indicated for controlling yautomatically not only the movements of ,the :pist-on :but also `for controlling an auxiliary exhaust means for the forward cylinder chamber infront of the piston to increase the power of the forward stroke of the latter.

Other .objects and the yadvantages inherent in the nature and the construction of the invention and resulting from its practical yapplication in the fart will become apparentes vthis specification proceeds. l

In the accompanying drawings:

Fig. 1 is la fragmentary longitudinal Isection `of a rock drill including a distributing valve embodying the invention in practical form, .the valve and a working piston controlled thereby being shown in initialrearward openative positions;

Fig. 2 ris a 'similar viewshowing the valve and pist-on in `fully `'opera-ted forward positions preparatory to return thereof lto original positions.;

Fig.,3 is a similar section 4to .thatof Fig. ,l but showing a modication of thevalveand its associated parts, the valve and piston occupying rearward initial operative positions as in said Fig. 1,; and

Fig. 4 illustrates the same modication as in l Fig. 3 with the valve and piston in extreme forward operatedpositions as in 2. z

Throughout the views the same references indicate the same or like parts.

, 2 In fluid actuated rock drills, theintensity of the blow delivered by *the 7piston lor :striking ele-` ment rof such a drill is "largely influenced by the ease'vofiiiow yof lfthe lmotive filuid :through fthe channels or passages :controlled 'by 'the distributing fvalve fthereof during the -fonward or .woririing stroke of t-he piston. It 'is important fthat lthe motive fluid lpassages be as Cfree as possible :from irregularities, :abrupt .or :indirect cons'tridtions or sharp bends so as to `provide a streamlined 'dow or at fleast straight line travel from filu'i'd usonner to Ethepiston. 'Itis thus .obvious that :introductionn-of iter-.tucus -or sharp :bends resulting from the -constructionwof the distributing ".valve sha-ll alsdbevavoided to .thesame-.end l Y Hence; .referring again :to the drawings, Vlin fthe practice of fthe invention a rook -drfill casing, generally indicatedet fil) contains alhammer pisf` ton il reciprocable *.withina cylinder 1,2 divided into a rear cylinder chamber 1:3 fand ialforwand cylinder chamber :M 'by meansA of an intermediately located :annular exhaust :groove or cham nel If5 communicating `with fthe atmosphere through a main eexhaust opening for port IB. 'Ilhe forward portion or shank 'Ill of @the -piston is flutedgat i118 and iguidedfinafront cylinder washer 4Nl'yvh'ich -forms a iifxed `part -of 'ther-casing, M. The Washer also 'provides :a lclosure for thefxtoxt end Vof `forward cylinder chamberild, whileithe rear fend of ltheicylinder 1chamber `Il is closed by a lvalve :cap 21) seated :againstashoulder 2l inra. counterbore 22 .in the leasing.` Valvefcap .'29 lis provided with a `plurality of :flu-id inlet passages or :ports :23,123 forsupplying motive fluid directly against fthe rear end vror face 2A of lfpiston il, as

will presently 4vbe explained. Located ,rearwardly of ysaid valve cap in :the samefcounterbore V2-2 isia valve .block 25, 'beyondcwhich is located .a ratchet ring .26 `(if vconventional type surrounding :a pluralityaof pawls Gnot .show-nl 4,carried by ,a .rifle :bar 21 :associated with :the hammer piston to :rotate the latten .A back head 28 completes rthe end closure of teasing 1:0 andlconfines the ratchet :ning 26 in -place @between the back :head-,and the :casing, said back headfbeing ,secured to [the latter by the-usual through -bolts ItG-not shown).

-Within the valve ca-p 20 and valve-block .-25 ,.is mounted the `frxed bushing 29 `virtuallylsuspended bylthe lends Ithereof, with fone `end secured in the valve cap and ftheother endsecuredvin tthe rear portion of the valve block. Ther-bushinglhas a lpair fof separate locating flanges 30, :3| frespectivelyengaging against inwardly rextending ilanges 32m-1d 33 of said valve fcap and valvelblok serving Lto retain fthe bushing in :place: The forV 3 ward end 34 of the Valve block is fitted upon the rearward projection 35 of the valve cap against shoulder 36 thereof, with the result that said valve cap 20, valve block 25, and bushing 29 together form a valve casing or chest for a hollow reciprocable distributing valve 31 surrounding the fixed bushing 29 generally without contact therewith and mounted for longitudinal sliding movement within said valve cap and valve block.

In order to supply motive fluid to the distributing valve, the throttle valve 38 is .rotatably mounted in back head 28 and controlled by hand lever 39, while the interior chamber 40 lthereof is connected to a continuous supply of `motive fluid under pressure (not shown). When the throttle valve is open, as illustrated, the motive fluid passes through passage 4I to chamber or reservoir 42 in the back head and thence through passages 43 within the ratchet ring 26 to fluid reservoir 44 in valve block 25. From this reservoir the fluid travels onward through several inlet ports 45 in block 25 to the annular passage 46 about bushing 29 and within the .hollow valve 31. Bushing 29 extends throughout the interior of the distributing valve and the position of the latter valve with respect to the bushing determines the further course of the fluid.` When 'the distributing valve and the piston occupy the rearward or initial operatlve position shown in Fig. 1, the motive fluid travels forwardly beneath an internal or inwardly directed flange 41 within distributing valve 31, over the shoulder formed by retaining flange 30, past the forward end 48 of the valve, into an annular distributing passage or groove 49 and thereafter escapes through the fluid inletl ports23, 23 opening therefrom into the rear cylinderchamber I3, where the force of the fluid is exerted against the rear face 24 of piston Il'to drive the same forward to the extreme operated position illustrated in Fig. 2.

However, during the forward travel of the piston, and approximately at the position indicated by broken line 50 (Fig. 2), said piston uncovers port in the cylinder wall above the piston, communicating through control valve 52 with fluid return flow passage 53 which in turn communicates with annular valve flange chamber 54, allowing the motive fluid in the rear cylinder chamber I3 suddenly to rush into annular chamber 54 as indicated by the broken arrows in Fig 2, and immediately exert pressure on the rear surface 55 of the valve shoulder or flange 56 tending to overcome the active fluid pressure on the forward end 48 of the valve as well as on the forward face 51 of internal flange 41 and thereby tend to displace the valve 31 forwardly into the position shown in said Fig. 2. Prior tosuch movement of the valve, the motive fluid impinges at 'high velocity against the rear face 58 of internal flange 41, and in passing forward between the latter and the shoulder 59 on bushing 2 9 toward ports '23, tends to produce a parjacent to the flange and renders the flange particularly responsive to changes in the velocity of the pressure fluid travelling forward within the valve through the annular passage 46 from reservoir 44. The flow of the pressure fluid between the bushing and said internal flange 41 is obviously somewhat restricted by the increase in the diameter of the bushing occasioned by the presence of shoulder 59. Hence, as already indicated, the velocity of the motive fluid flowing past the internal flange creates a partial vacuum beyond the flange which, with the pressure of the motive fluid impinging on rear flange face 58 tends suddenly to shift the valve forwardly despite counter pressures due to the effect of the differential areas upon the forward and rear faces of the valve and its flanges, while in similar fashion rearward shifting of the valve tial vacuum on front face 51 of the flange and thus assists in shifting the valve forward. In the attained forward position of the valve, the end 48 thereof overlies shoulder or flange 30 of bushing 29 in contact with the periphery thereof and cuts off further supply of fluid to rear cylinder chamber I3.

In fact, an importantl feature of the invention is the arrangement of the internal flange 41 on the distributing valve 31 in a position to'vsurround the shoulder 59 upon bushing 29 which increases the diameter of the latter 9&1-

.is likewise facilitated. When the valve is in its forward position, the internal flange 41 tends to shift it rearwardly due to the greater area at its front face 51 than at its rear face 58, both faces then being under the same static pressure per unit area. On the other hand, when the valve is in its rearward position (Fig. 1) the internal flange tends to shift it forward due to the preponderance of dynamic force on rear face 58 as compared with the reduced pressure against front face 51 and in spite of the smaller area of the rear face. The flange 41 thus assists in the tripping of the valve 31 in both directions, resulting in a Yquicker, more positive, valve action, greater power and a reduction in air consumption.

` It is, of course, understood that the stroke of the piston is very swift, so that the portion of the movement of the piston occurring from the point indicated by the broken line 60 to that indicated by line 50 while uncovering port 5I is substantially instantaneous, and shortly thereafter, when the valve 31 has been shifted so as to cut oil the motive fluid, the piston has attained the final operated position and uncovered the annular exhaust groove I5 for release of the compressed fluid from cylinder chamber I3 through exhaust port I6.

At this juncture it may be mentioned that prompt or even abrupt shifting of valve 31 in the forward direction is facilitated by the presence of a fluid clearance or breather port 6I exposing the forward face 62 of valve flange 56 to the atmosphere to prevent entrapment of air and building up of an air cushion in front of the valve. In somewhat similar fashion, the rear fluid clearance or bleeder port 63 is provided for clearing out excess pressure fluid from passage 53 and flange chamber 54 during part of the rearward or return stroke of the piston as will immediately appear.

When the distributing valve has been displaced forwardly to occupy the position shown in Fig. 2 as already described, shoulder portion 64 which includes a reduced portion upon the rear of the valve 31 clears the inner edge of the rear face 65 of the annular groove or port 6B in valve block 25 surrounding the valve, so that the motive fluid arriving through ports 45 from reservoir 44 will proceed between said valve shoulder portion and the edge of face 65 into said annular groove 66. As the latter connects with the piston return passage 61 which in turn opens into the forward cylinder chamber I4 through a port 68, the motive fluid will immediately exert its pressure against the effective front working face escasas 69 of the piston and drive the `same rreamar again to the startngpOSitiUnOfFig. 1. During the initial par-t of the return stroke when the-rear end of the piston has Vagainnovered the annular exhaust groove I and :is travelling from the 'rear edge :of said groove i5 to approximately the position indicated vby broken line 80 (Fig. 2l, fthe piston covers the yport 5| above it while partly compressing :the duid in rear :cylinder chamber I3, initially communicatingthe pressure thus producedto said port 5| and 1passageli. After 'the piston has covered port '55| during ysuch rearward movement, further communication `between `.the latter 4and the rising pressure fin the cylinder chamber is cutoff, but as port 5| :and the passage 5'3 are connected to the iiange chamber'M which is vented to the atmosphere by rearbl-eeder port 63 theluid in .said passagewill rin great escape' through the latter so -as to clear `pressure fluid from behind valve iiange 56 preparatory 'to rearward shiftin-g'of valve 31. 1When the forward end @'69 of the piston has uncovered ythe annular fluid in front cylinder chamber 14 through exhaust opening lli, the piston will `also "have attained a 'predetermined position pri-or to actually reaching the fully returned initial position, in which the fluid pressure resulting from piston compression has ri-sen `to a sufficient 'height `to act through ports 23 against forward-'end 48-of the valve and `tend to overcome the motive fluid pressure on the 'rear face '10 and of the fluid against flange face thereof. As the piston-compressed fluid also immediately reaches front face '51 of the `internal flange 41, the -uid pressure exerted on the relatively large area thereof overcomes the effect of any ilu-id pressure exerted in the opposite direction on the relatively smaller area of rear face 58 Aof the same flange, Vwith the result that distributing valve 31 is quickly shiftedback to the position of Fig. l, in which ycommunieation between ports 45 and rear annular groove 68 is cut off and the Cycle-of bothpiston and valve completed with both ready for a new cycle of operation. Whatever slight fluid pressure may bepresent in passage 53 and chamber 54 will be-fully released forwardly into cylinder chamber |4 through rport 5| in front of piston II, to pass out through 'annular exhaust 4groove l5 and exhaust port |6 as indicated by the -arrowsin said-jgroove and port AFig. l. It is to 'be noted thaftiinfthe rearward position -of valve -3|,lthe=rear face I8 of said valve engages closely against the shoulder or rear stop TI in the valve block (Fig. 1) so that said shoulder virtually covers the rear face and initially prevents the motive fluid from impinging on said face to impart a forward impulse. Obviously, when the valve has begun to shift forwardly, the pressure fluid gains access to the rear face 18 and exerts its force thereon to serve as a holding force when this valve reaches the forward position, in the meantime assisting in the forward shifting of the valve.

In constructing the valve, care is taken to ensure that the axial distance extending from the forward end of shoulder portion 64 on the rear of valve 31 to the forward end 48 of said valve is suliciently long to prevent the edge of rear face 65 of annular groove 66 from passing motive fluid from ports 45 while said forward end 48 exposes the shoulder or flange 30 thereto so as to allow the iiuid to pass through passage 49 to ports 23. vThus only one of the ends of the valve will be effective to pass motive iiuid at any given time,

and `proper foperai'on will therefore be reasonably certain.' l l JIt slight* modification of 'the'valve structure is illustrated .in Figs. '3 and ewherein `the Vrear `portion of valve 12 and valve :block S13-with its-contained pa'ssagesland ports include certain `features departing `:from the 7corresponding valve 31 and valve lblockz of 1 and 2, the yother parts and afoatures `and leven the 'general operation being fthe same `as in `theamparann illustrated in said 'first two "figures, except as will now be described. i

'Referring 'particularly to Fig. 3, the piston occupies its initial rear-position in cylinder chamber 13 which it is assumed just to `have attained in completing a forward stroke and a rear return stroke, so that-the valve 12 has been shifted to its rear position while the expanded or spent motive jfluid` isbeing released through armular exhaust groove i5 and port |26 from cylinder chamber I4.

As it Iis important that the forward 'cylinder chamber be promptly cleared of all fluid under pressure so that the subsequent forward driving stroke lof *the piston 'shall occur with maximum force, auxiliary exhaustlnglmeairs are called upon torserve simultaneously with theannular exhaust groove Iand exhaust To this end the erstwhile piston return passage il is caused tov be instantly vented into an exhaust passage or port Y when `the distributing valve .is shiftedofrom the forwardpositiontofitsrearsposition. i. l

Hence vthe valve 12 4is provided with an exterior .flange '14, interior ilange 15, forward end 1S :and :rearward shoulder portion il, yand vin construction and operation corresponds to Avalve 31 and its :exterior flange 56, interior flange '41, forward end wand res/r shoulder portion 64, respectively, in Figs. land i2, cooper-ating with the passages and ports in Valve block 13.1su'bstantially as previously described with. reference to 'valve block 125.. Between the rear annulasgroove FIB :and the valve flange chamber '1S is a further .annular exhaust groove 8| in valve olock 13, connecting `with the atmosphere through auxiliary exhaust 82 (Fig. 3), said annular `exhaust groove surrounding the valve 12 and being :separated from annular groove 'I8 by a `partition "88; Furthermore, the valve has an exteriorannularfgroove 'forming :a neck 84 upon an intermediate portion thereof Aseparated from the `rear shoulder portion 'Hviby means ci a relatively wide and low rib 85.

Thus in the position illustrated in Fig. 3, the valve I2 cuts olf communication between the passages or ports 86 and annular groove 18, but the latter, being directly connected to the return passage 61, communicates freely with the further annular exhaust groove 8| over the neck 84 on the valve past partition 83, so that the air in cylinder chamber I4 exhausts through the return passage 61, annular exhaust groove 8| and port 82 to atmosphere, simultaneously with, and also subsequently to, the escape of pressure fluid through annular exhaust groove |5 and the main exhaust port I6. The auxiliary exhaust passages 18, 8| and 82 thereby cooperate with passage 61 in preventing the compression of air by the piston near the end of its forward stroke. This feature has especial application to longstroke machines.

When the piston |I has travelled through the major portion of its forward driving stroke so that valve T2 is displaced to its forward position as shown in Fig. 4, the rib or flange 85 will also have been shifted so as to register with the partition 83 which fits closely about the same and will be effective to cut off the connection between the annular groove 18 and annular exhaust groove 8l. In this position the rear shoulder portion 11 of valve 12 passes motive fluid from the ports 88 and from reservoir 81 to annular groove 18 past said shoulder portion 11, and thence through piston return passage 51 to the forward cylinder chamber I4 for effecting the return stroke of the piston, after which the cycle will be repeated as long as motive fluid is supplied to Valve chamber 40 of throttle valve 38. In the rearward position of valve 12, the rear holding area on end 88 is initially disposed against shoulder 89 in valve block 13 as in the case of rear end 18 on valve 31 `initially engaging against shoulder 1I in valve block 25 previously described. Likewise, the relatively larger area of front face 91| and the relatively smaller area of rear face 92 on internal flange 15 function substantially as in the case of the corresponding front and rear faces 51 and 58 on flange 41 of valve 31. Thus in both forms of the valve, the internal flange serves to speed up shifting of the valve in both directions. From the foregoing it is manifest that the form and location of the distributing valve allows the same to control the ow of motive fluid to the piston auto matically in both directions in effective manner and especially facilitates the flow of pressure fluid to the rear of said piston along a substantially streamlined path, while in -a modified form the valve also controls auxiliary exhausting of the forward cylinder chamber to clear the path of the piston for its forward stroke.

Obviously variations may be resorted toand parts or features used without others within the scope of the invention as defined in the appended claim.

What is claimed is:

In a fluid pressure actuated rock drill comprising a cylinder having a piston reciprocable therein, a valve chest provided with a bored surface in its rear portion adapted for seating,

an annular distributing valve mounted in said chest for axial reciprocation andv having at its forward extremity a bored surface and adjacent its rear extremity a perlipheral surface adapted to cooperate with said bored seating surface in the valve chest, a bushing coaxially disposed within the valve and spaced therefrom to provide an annular passageway therebetween and having a peripheral surface adapted to cooperate with the bored surface of the valve, means for delivering live air constantly to the rear end of the annular passageway, a rear cylinder port or ports connecting the front end of the annular passageway with the rear end of the cylinder and adapted t-o be uncovered by the valve in its rearward movement, a front cylinder passage connecting the rear end of the annular passageway with the front end of the cylinder and arranged to be uncovered upon forward movement of the valve, means for applying a pressure to the valve tending to hold the valve in each of its extreme positions, and means for tripping vthe valve automatically in response to the movements of the piston, said tripping means comprising an internal flange on the valve extending toward said bushing, the front face of the flange having a larger area than the rear face and being in constant communication with said annular passageway whereby the resultant static pressure on the flange tends to unseat the valve when in its forward position, the inner edge of the flange being closely spaced from the bushing whereby in the rear position of the valve the impinging of air against the rear face of the flange and the reduction of pressure on the front face of the flange combine to produce a resultant of force on the flange tending to unseat the valve, said valve chest being provided with an auxiliary exhaust port connecting to the atmosphere an exhaust groove adjacent the outlet passage to the front end of the cylinder, said valve being provided adjacent its rear peripheral seat with a portion of reduced diameter vor neck adapted to connect said outlet passage to the exhaust groove upon reciprocation of the valve to its rearward position whereby to provide an auxiliary exhaust passage to diminish the compression of air by the piston near the end of the forward stroke.

HENRY O. FOSSUM.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS y Date 

